[BUGFIX] Apc Cache backend has side effects

If two caches use the APC cache backend,
one cache can write and get entries from the
 other by just using the same key!
So the backend should also use cache id as prefix

Change-Id: I46f7a04386427efb2e1753bef6dfa588508d076c
Fixes: #38135
Releases: 4.5,4.6,4.7,6.0
Reviewed-on: https://review.typo3.org/17473
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel